scholarly journals Light reduction and moisture stress: effects on growth and water relations of western larch seedlings

1985 ◽  
Vol 15 (1) ◽  
pp. 72-77 ◽  
Author(s):  
Nan C. Vance ◽  
Steven W. Running

Ten-week-old western larch (Larixoccidentalis Nutt.) seedlings were grown in a greenhouse under 70, 37, and 27% full sunlight from late July to early October. In August, seedlings under each light treatment were repetitively water stressed until predawn leaf water potential (Bψ1) reached one of three levels: no stress (> −0.4 MPa), moderate stress (−0.7 to −1.0 MPa), and severe stress (−1.5 to −1.8 MPa). Moisture stressing significantly reduced height and diameter of seedlings grown under 70% light. Light reduction reduced shoot and root biomass accumulation. A positive linear relation was found between root dry weight and light intensity. The largest seedlings (on a weight basis) received the highest light, were unstressed, and had the lowest shoot/root ratios. Terminal bud set was not affected by light reduction or moisture stressing but occurred under a 14-h photoperiod and reduced nighttime temperatures. Stressed and shaded seedlings had significantly reduced diurnal K1 and stress-cycled seedlings showed an adjustment to stressing. The K1 of unstressed seedlings was correlated with humidity deficit (ABHD), and K1 of stressed seedlings, with Bψ1, and ABHD. Maximum K1 declined with decreasing Bψ1, but not to a level indicating complete stomatal closure.

2012 ◽  
Vol 39 (1) ◽  
pp. 53-61 ◽  
Author(s):  
Maria Balota ◽  
Steve McGrath ◽  
Thomas G. Isleib ◽  
Shyam Tallury

Abstract Water deficit, i.e., rainfall amounts and distribution, is the most common abiotic stress that limits peanut production worldwide. Even though extensive research efforts have been made to improve drought tolerance in peanut, performance of genotypes largely depends upon the environment in which they grow. Based on greenhouse experiments, it has been hypothesized that stomata closure under high vapor pressure deficit (VPD) is a mechanism of soil water conservation and it has been shown that genotypic variation for the response of transpiration rate to VPD in peanut exists. The objective of this study was to determine the relationship between stomatal conductance (gs) and VPD for field grown peanut in Virginia-Carolina (VC) rainfed environments. In 2009, thirty virginia-type peanut cultivars and advanced breeding lines were evaluated for gs at several times before and after rain events, including a moisture stress episode. In 2010, eighteen genotypes were evaluated for gs under soil water deficit. In 2009, VPD ranged from 1.3 to 4.2 kPa and in 2010 from 1.78 to 3.57 kPa. Under water deficit, genotype and year showed a significant effect on gs (P  =  0.0001), but the genotype × year interaction did not. During the water deficit episodes while recorded gs values were relatively high, gs was negatively related to VPD (R2  =  0.57, n  =  180 in 2009; R2  =  0.47, n  =  108 in 2010), suggesting that stomata closure is indeed a water conservation mechanism for field grown peanut. However, a wide range of slopes among genotype were observed in both years. Genotypes with significant negative relationships of gs and VPD under water deficit in both years were Florida Fancy, Gregory, N04074FCT, NC-V11, and VA-98R. While Florida Fancy, Gregory, and NC-V11 are known to be high yielding cultivars, VA-98R and line N04074FCT are not. The benefit of stomatal closure during drought episodes in the VC environments is further discussed in this paper.


2013 ◽  
Vol 31 (1) ◽  
pp. 39-42
Author(s):  
Joshua R. Pool ◽  
Jason J. Griffin ◽  
Cheryl R. Boyer ◽  
Stuart L. Warren

The Midwest and southern Great Plains are known for historic and severe droughts. More common, however, are short-term recurring drought events that can limit tree survival. The pressure of environmental stress combined with numerous diseases and pests are decimating existing Pinus L. spp. (pine) plantings and driving the effort to identify alternative species. Four species of conifer were subjected to recurring moderate or severe drought to observe the effects on growth and photosynthesis. Species evaluated were: Abies nordmanniana (Nordmann fir), Cupressus arizonica (Arizona cypress), Picea engelmannii (Engelmann spruce), and Thuja × ‘Green Giant’ (‘Green Giant’ arborvitae). Recurring drought reduced height and growth index of T. × ‘Green Giant’. However, photosynthesis and root growth were unaffected by drought treatments. In contrast, reduced Pnet was the only detectable effect of recurring drought in P. engelmannii. Growth of A. nordmanniana was not affected by drought. When subjected to drought, C. arizonica reduced shoot dry weight, while maintaining photosynthesis and root growth. Overall, C. arizonica was able to maintain growth of roots and shoots as well as maintain photosynthesis which may be an advantage in the harsh climate of the Midwest and southern Great Plains.


2006 ◽  
Vol 61 (9-10) ◽  
pp. 619-624 ◽  
Author(s):  
Xinkun Wang ◽  
Yinghua Huang ◽  
Andrew J. Mort ◽  
Yuhong Zeng ◽  
Charles G. Tauer ◽  
...  

AbstractNeedles from 17 different Taxus x media cultivars, belonging to 4 groups showing different growth characteristics, were analyzed using high performance liquid chromatography for their content of 10-deacetylbaccatin III, baccatin III, cephalomannine and paclitaxel (Taxol®). The 4 Taxus x media cultivar groups were: 1.) medium to fast growing and upright form; 2.) slow growing and upright form; 3.) fast growing and spreading form; and 4.) slow growing and spreading form. The purpose of this study was to identify yew cultivars of fast growth rate, upright growth and high taxane content in their needles. The highest content of paclitaxel was found in ‘Coleana’ of group 1 (378 μg/g of the extracted dry weight). Three cultivars in group 1, ‘Coleana’, ‘Stovekenii’ and ‘Hicksii’, make good candidates for taxane extraction because of their high paclitaxel and 10-deacetylbaccatin III content, fast biomass accumulation and upright growing form. They are also good starting materials to develop alternative methods for the production of paclitaxel and its analogous compounds through modern biotechnology approaches.


Weed Science ◽  
1993 ◽  
Vol 41 (3) ◽  
pp. 335-340 ◽  
Author(s):  
Frank S. Rossi ◽  
Joseph M. Di Tomaso ◽  
Joseph C. Neal

Investigations of smooth crabgrass growth and fenoxaprop-ethyl retention, foliar penetration, translocation, and metabolism were conducted at various soil moisture levels using a polyethylene glycol (PEG) semipermeable membrane system. The activity of fenoxapropethyl was significantly reduced at higher levels of moisture stress and this antagonistic effect was greater with increased duration of water deficit following herbicide application. Fenoxaprop-ethyl spray retention decreased linearly (23% total reduction) as soil matric potential (Ψm) decreased from −0.01 to −0.1 MPa. Foliar penetration and translocation of14C-fenoxaprop-ethyl applied on the third true leaf were not affected by level or duration of moisture stress. Only 2% of the absorbed radioactivity was translocated out of the treated leaf for each moisture stress level and duration. As the soil Ψm decreased (−0.01 to −1.0 MPa) the relative levels of fenoxaprop-ethyl increased by 76 and 65% after a 48- and 96-h postapplication moisture stress period, respectively. In contrast, fenoxaprop acid decreased by 59 and 44% after 48 and 96 h of moisture stress, respectively. The relative level of fenoxaprop acid was linearly correlated to the antagonistic effect on shoot dry weight. These results suggest that decreased spray retention and, particularly, alterations in fenoxaprop-ethyl metabolism contribute to reduced fenoxaprop-ethyl activity observed in moisture-stressed smooth crabgrass.


1979 ◽  
Vol 71 (1) ◽  
pp. 86-90 ◽  
Author(s):  
N. N. Momen ◽  
R. E. Carlson ◽  
R. H. Shaw ◽  
O. Arjmand

2020 ◽  
Vol 34 (6) ◽  
pp. 807-813
Author(s):  
Benjamin H. Lawrence ◽  
Jason A. Bond ◽  
Bobby R. Golden ◽  
Thomas W. Allen ◽  
Daniel B. Reynolds ◽  
...  

AbstractOff-target paraquat movement to rice has become a major problem in recent years for rice producers in the midsouthern United States. Nitrogen (N) fertilizer is applied to rice in greater quantity and frequency than all other nutrients to optimize rice yield. Two separate field studies were conducted from 2015 to 2018 in Stoneville, MS, to assess whether starter N fertilizer can aid rice recovery from exposure to a sub-lethal concentration of paraquat and to evaluate rice response to different N fertilizer management strategies following exposure to a sub-lethal concentration of paraquat. In both studies, paraquat treatments consisted of paraquat at 0 and 84 g ai ha–1 applied to rice in the two- to three-leaf (EPOST) growth stage. In the starter fertilizer study, N fertilizer at 24 kg ha–1 as ammonium sulfate (AMS) was applied to rice at spiking- to one-leaf (VEPOST), two- to three-leaf (EPOST), or three- to four-leaf (MPOST) growth stages before and after paraquat treatment. In the N fertilizer timing study, N fertilizer at 168 kg N ha–1 was applied in a single four-leaf to one-tiller (LPOST) application or two-, three-, and two four-way split applications. Despite starter N fertilizer applications, paraquat injured rice ≥41%, reduced height 57%, reduced dry weight prior to flooding 77%, delayed maturity 10 d, reduced dry weight at maturity 33%, and reduced rough rice yield 35% in the starter fertilizer study. Similarly, in the N fertilizer timing study, paraquat injured rice ≥45%, reduced height 14%, delayed maturity 10 d, reduced dry weight at maturity 44%, and reduced rough rice yield 50% for all N fertilizer management strategies. Both studies indicate that severe complications in growth and development can occur from rice exposure to a sub-lethal concentration of paraquat. In both studies, manipulation of N fertilizer management did not facilitate rice recovery from early-season exposure to paraquat.


1980 ◽  
Vol 10 (4) ◽  
pp. 549-554 ◽  
Author(s):  
M. M. Larson

Northern red oak (Quercusrubra L.) 1-0 seedlings were planted in plastic tubes with a rubber moisture barrier placed around taproots at midpoint so that upper and lower sections of the root system could be independently watered with polyethylene glycol solutions to induce various soil moisture stress conditions. Trees were also grown at two relative humidity (RH) levels.In the first of two studies, soil moisture stress levels were −1/3, −3, −6 bars (1 bar = 105 Pa), and RH's were 75 and 45%. Root regeneration (largely confined to cut end of lower taproot) and top growth decreased, and dieback of planted stems increased, as soil moisture stress of either upper or lower root sections increased. When both sections were −6 bars, root regeneration was nil.In the second study, upper root soil moisture stress levels included a −12-bar treatment which reduced dry weight of leaves and roots to about one-half that of unstressed plants. However, a unit increase in stress to lower root sections was 1.5 to 4 times more inhibitory to growth than a similar stress to upper root sections. Low RH decreased several measures of seedling growth, increased stem dieback, and prolonged time to budbreak from 6 to 12 days for most soil moisture treatments.These studies demonstrate that root regeneration is very sensitive to soil moisture stress on lower roots, where most of the new roots originate, and moderately sensitive to stress on upper roots and to atmospheric stress on shoots.


2007 ◽  
Vol 21 (1) ◽  
pp. 230-234 ◽  
Author(s):  
Peter H. Sikkema ◽  
Christy Shropshire ◽  
Nader Soltani

Three field trials were conducted over a 2-yr period (2004 and 2005) at Exeter and Ridgetown, Ontario to evaluate the tolerance of eight market classes of dry beans to KIH-485 applied PRE at 210 and 420 g ai/ha. KIH-485 PRE caused as much as 67% visual injury in small-seeded and 44% visual injury in large-seeded dry beans. KIH-485 applied PRE at 420 g/ha reduced plant height up to 47% at Ridgetown and 8% at Exeter in 2004, and reduced height of brown and white bean by 15 and 19%, respectively, but had no effect on the height of the other beans in 2005. Shoot dry weight was not affected at Exeter in 2004 but was reduced by 46% at Ridgetown in 2004 and 14% at Exeter in 2005. In 2004, seed moisture content increased by 5, 6, and 12% in black, otebo, and pinto beans, respectively. Seed yield was reduced up to 27% at Ridgetown and 11% at Exeter in 2004 but was not affected at Exeter in 2005. On the basis of this research, KIH-485 PRE causes unacceptable injury in some dry bean market classes.


1977 ◽  
Vol 4 (6) ◽  
pp. 857 ◽  
Author(s):  
MF Beardsell

Maize (Zea mays L. cv. XL45) plants were grown from seed in controlled-environment rooms. Twice-daily weighings of the plants and containers for 7 days reduced height, and removing plants from the rooms for two 20-min periods daily for 7 days gave significant reductions in stem and leaf dry weights and total leaf area. Transpiration rates were not affected by either of these treatments. Short-term removal from the rooms (up to 10 min daily) produced no significant reductions in plant characteristics. Measuring leaf lengths daily for 10 days resulted in significant reductions in stem dry weight and plant height. It is suggested that control plants should always be subjected to the same degree of handling as treated plants.


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